Ethnic differences in vitamin D status, bone and body composition in South Asian indian and caucasian men

Background: High prevalence of metabolic abnormalities and poor bone health in ethnic minorties may stem from differences in body composition and alterations in endocrine milieu. South Asian Indians (SAIs) are at greater risk for metabolic syndrome (MetS) and poor bone health than Caucasians. Often these differences are reported later in life and/or in a resident immigrant population compared to a Caucasian population. In this study, we determined whether vitamin D status, bone, body composition differed in young SAIs and Caucasians. Notably we compared differences amongst recent SAI immigrants and Caucasians. Methods: We examined differences in bone density, body composition, serum 25-hydroxy vitamin D (s25(OH)D), parathyroid hormone (sPTH), vitamin D binding protein (sDBP), osteocalcin (sOC), and dietary intakes in young healthy SAI and Caucasian men. Results: Sixty men (N = 30 SAIs and N = 30 Caucasians) with a mean age of 27.8 +/- 7.4 years completed the study. Compared to the Caucasians, SAIs had statistically significantly lower s25(OH)D and higher sPTH (p < 0.05). We also found that s25(OH)D was negatively associated with sPTH only among the SAIs (r = - 0.389, p = 0.037). Also, lean mass% (LM%) and fat-free mass% (FFM%) were lower in SAIs (p < 0.05) compared to caucasians. s25(OH)D correlated with nearly all body composition parameters, while sPTH correlated negatively with LM% and FFM%, and positively with FM% (all p < 0.05) in the Caucasian group. Bone mineral density at most sites were also significantly lower (p < 0.05) in the SAI's compared to caucasians. Conclusion: Young SAIs have a poor vitamin D status and less favorable bone and body composition parameters compared to Caucasians. These findings highlight the possible complex interplay between skeletal and metabolic health in different ethnicities which may be evident early on in life. Interventions to improve bone and metabolic health should therefore target younger ethnic minorities.